Three-dimensional printed dental appliances using lattices

ABSTRACT

Method and apparatus for fabricating an oral appliance are described for correcting malocclusions on a dentition of a subject. A three-dimensional representation of the dentition may be captured and a free-form structure having a lattice structure which matches at least part of a surface of the dentition is generated. The lattice structure defines a plurality of open spaces such that the free-form structure is at least partially transparent. The lattice structure may then be manufactured by impregnating or covering a coating into or upon the lattice structure such that the oral appliance is formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/238,532 filed Oct. 7, 2015, which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for thefabrication of dental appliances such as retainers and aligners usingthree-dimensional (3D) printing processes. More particularly, thepresent invention relates to methods and apparatus for fabricatingdental appliance using three-dimensional (3D) printing processes wherethe appliances may be formed to have hollow shapes with complexgeometries using tiny cell lattice structures.

BACKGROUND OF THE INVENTION

Orthodontics is a specialty of dentistry that is concerned with thestudy and treatment of malocclusion, which can be a result of toothirregularity, disproportionate facial skeleton relationship, or both.Orthodontics treats malocclusion through the displacement of teeth viabony remodeling and control and modification of facial growth.

This process has been traditionally accomplished by using staticmechanical force to induce bone remodeling, thereby enabling teeth tomove. In this approach, braces consisting of an archwire interfaces withbrackets that are affixed to each tooth. As the teeth respond to thepressure applied via the archwire by shifting their positions, the wiresare again tightened to apply additional pressure. This widely acceptedapproach to treating malocclusion takes about twenty-four months onaverage to complete, and is used to treat a number of differentclassifications of clinical malocclusion. Treatment with braces iscomplicated by the fact that it is uncomfortable and/or painful forpatients, and the orthodontic appliances are perceived as unaesthetic,all of which creates considerable resistance to use. Further, thetreatment time cannot be shortened by increasing the force, because toohigh a force results in root resorption, as well as being more painful.The average treatment time of 24-months is very long, and furtherreduces usage. In fact, some estimates provide that less than half ofthe patients who could benefit from such treatment elect to pursueorthodontics.

Kesling introduced the tooth positioning appliance in 1945 as a methodof refining the final stage of orthodontic finishing after removal ofthe braces (de-banding). The positioner was a one-piece pliable rubberappliance fabricated on the idealized wax set-ups for patients whosebasic treatment was complete. Kesling also predicted that certain majortooth movements could also be accomplished with a series of positionersfabricated from sequential tooth movements on the set-up as thetreatment progressed. However, this idea did not become practical untilthe advent of three-dimensional (3D) scanning and computer and used byAlign Technologies and others such as OrthoClear, ClearAligner andClearCorrect to provide greatly improved aesthetics since the devicesare transparent.

SUMMARY OF THE INVENTION

The present invention relates to free-form structures fitting thesurface of a body part. In particular embodiments, the free-formstructures include oral appliances or aligners, although the devices andmethods described are not so limited.

One method for fabricating an oral appliance may generally comprisecapturing a three-dimensional representation of a dentition of a subjectand generating a free-form structure having a lattice structure whichmatches at least part of a surface of the dentition, wherein the latticestructure defines a plurality of open spaces such that the free-formstructure is at least partially transparent. The lattice structure maythen be manufactured by impregnating or covering a coating into or uponthe lattice structure such that the oral appliance is formed.

One or more oral appliances may thus be manufactured where eachsubsequent oral appliance is configured to impart a movement of one ormore teeth of the subject and is intended to be worn by the subject tocorrect for any malocclusions.

Generally, the oral appliance may comprise the lattice structure whichis configured to match at least part of a surface of a dentition of thesubject, wherein the lattice structure defines a plurality of openspaces such that the free-form structure is at least partiallytransparent. A coating may impregnate or cover into or upon the latticestructure and at least one dental attachment structure may be formed aspart of the lattice structure, wherein the dental attachment structureis located in proximity to one or more teeth to be moved.

The system provides free-form structures fitting the surface of a bodypart, which are at least partially made by additive manufacturing. Thefree-form structures may comprise a basic structure which includes alattice structure and a coating material provided thereon. The latticestructure may be impregnated in and/or enclosed by the coating materialwhich may include, e.g., polymeric or ceramic materials and metals.Furthermore, the coating material may include different regions ofvarying thickness or other features incorporated into the material. Thepolymer may include a number of different types, e.g., silicone,polyurethane, polyepoxide, polyamides, or blends thereof, etc. Inalternative embodiments, the lattice structure may be impregnated inand/or enclosed by a foamed solid.

In certain embodiments, the lattice structure may be defined by aplurality of unit cells with a size between, e.g., 1 and 20 mm. In otherembodiments, the lattice structure may be provided with varying unit,cell geometries having cell varying dimensions and/or varying structuredensities. In other embodiments, the lattice structure may be comprisedof at least two separate lattice structure parts movably connected toeach other and integrated into the structure.

In certain embodiments, the free-form structure may further include oneor more external and/or internal sensors (e.g. pressure and/ortemperature sensors) and/or one or more external and/or internal markers(e.g. position markers). Such markers can be read externally todetermine current tooth movement to help the practitioner in decidingfuture movement adjustments, if needed.

In certain embodiments, the free-form structure may further include oneor more agents disposed externally and/or internally such as variouschemicals or drugs, e.g., tooth whitening materials, insulin which canbe slowly delivered orally to a diabetic patient, etc. Such chemicals,drugs, or medicine can also be incorporated to loosen up the gums and/ortendons to enable teeth move faster, wound treatments, etc.

In certain embodiments, the free-form structure may further comprise oneor more external and/or internal locators so that, when such a device ismisplaced, the user can use a mobile computer to detect the location andfind the device. The locator can include any number of devices, e.g.,magnets, wireless proximity detectors, optical proximity detectors, etc.

The free-form structures can also be further configured to havedifferent stiffness values in different regions of the structureutilizing a number of different configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description of the figures of specific embodiments of theinvention, is merely exemplary in nature and is not intended to limitthe present teachings, their application or uses. Throughout thedrawings, corresponding reference numerals indicate like orcorresponding parts and features.

FIG. 1A shows an exemplary process for fabricating a dental applianceusing a lattice structure.

FIG. 1B shows an exemplary process for fabricating a dental appliancewith varying material thickness using a lattice structure.

FIG. 2A shows a perspective view of an example of a basic structureformed into a bottom half and a top half for a dental applianceutilizing a lattice structure which may be used in a 3D printingprocess.

FIG. 2B shows a detail exemplary view of the openings in a latticestructure.

FIG. 2C shows an exemplary end view of a lattice structure havingseveral reticulated layers.

FIG. 2D shows an exemplary end view of a lattice structure havingregions comprised only of the coating material.

FIG. 2E shows a detail perspective view of a lattice structure andcoating having a feature such as an extension formed from the surface.

FIG. 2F shows a detail perspective view of a lattice structure andcoating having different regions with varying unit cell geometries.

FIG. 2G shows a detail perspective view of a lattice structure andcoating having different regions formed with different thicknesses.

FIG. 2H shows an exemplary end view of a lattice structure havingregions with a coating on a single side.

FIG. 2I shows a perspective view of an aligner having at least oneadditional component integrated.

FIG. 2J shows an exemplary end view of a lattice structure a hinge orother movable mechanism integrated along the lattice.

FIG. 2K shows a perspective view of an aligner having one or more(internal) channels integrated.

FIG. 3 shows a perspective detail view of a portion of an aligner havingan area that is machined to have a relatively thicker material portionto accept an elastic.

FIGS. 4A and 4B illustrate a variation of a free-form dental appliancestructure having a relatively rigid lattice structure and one or morefeatures for use as a dental appliance or retainer.

FIG. 4C shows a partial cross-sectional view of as suction featurefabricated to adhere to one or more particular teeth.

FIG. 4D shows a perspective view of a portion of the aligner havingregions configured to facilitate eating or talking by the patient.

FIG. 4E shows a perspective view of a portion of the aligner havingdifferent portions fabricated to have different areas of varyingfriction.

FIG. 4F shows a perspective view of a portion of the aligner having aparticulate coating.

FIGS. 5A to 5D show various views of examples of lattice structuressuitable for forming dental appliances.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with respect to particularembodiments but the invention is not limited thereto but only by theclaims. Any reference signs in the claims shall not be construed aslimiting the scope thereof.

As used herein, the singular forms “a”, “an”, and “the” include bothsingular and plural referents unless the context clearly dictatesotherwise.

The terms “comprising”, “comprises” and “comprised of” as used hereinare synonymous with “including”, “includes” or “containing”, “contains”,and are inclusive or open-ended and do not exclude additional,non-recited members, elements or method steps. The terms “comprising”,“comprises” and “comprised of” when referring to recited members,elements or method steps also include embodiments which “consist of”said recited members, elements or method steps.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order, unless specified. It is to be understood that theterms so used are interchangeable under appropriate circumstances andthat the embodiments of the invention described herein are capable ofoperation in other sequences than described or illustrated herein.

The term “about” as used herein when referring to a measurable valuesuch as a parameter, an amount, a temporal duration, and the like, ismeant to encompass variations of +/−10% or less, preferably +/−5 % orless, more preferably +/−1% or less, and still more preferably +/−0.1%or less of and from the specified value, insofar such variations areappropriate to perform in the disclosed invention. It is to beunderstood that the value to which the modifier “about” refers is itselfalso specifically, and preferably, disclosed.

The recitation of numerical ranges by endpoints includes all numbers andfractions subsumed within the respective ranges, as well as the recitedendpoints.

All documents cited in the present specification are hereby incorporatedby reference in their entirety.

Unless otherwise defined, all terms used in disclosing the invention,including technical and scientific terms, have the meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. By means of further guidance, definitions for the terms used inthe description are included to better appreciate the teaching of thepresent invention. The terms or definitions used herein are providedsolely to aid in the understanding of the invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment, but may. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would beapparent to a person skilled in the art from this disclosure, in one ormore embodiments. Furthermore, while some embodiments described hereininclude some but not other features included in other embodiments,combinations of features of different embodiments are meant to be withinthe scope of the invention, and form different embodiments, as would beunderstood by those in the art. For example, in the following claims,any of the claimed embodiments can be used in any combination.

The system described herein is related to the fabrication of dentalappliances such as retainers and aligners using three-dimensional (3D)printing processes. The appliance may be formed to have hollow shapeswith complex geometries using tiny cells known as lattice structures.Topology optimization can be used to assist in the efficient blending ofsolid-lattice structures with smooth transitional material volume.Lattice performance can be studied under tension, compression, shear,flexion, torsion, and fatigue life.

Free-form lattice structures are provided herein, which fit at leastpart of the surface, e.g. external contour, of a body part.Specifically, the embodiments described may utilize free-form latticestructures for forming, or fabricating appliances which are designed forplacement or positioning upon the external surfaces of a patient'sdentition for correcting one or more malocclusions. The free-formstructure is at least partially fabricated by additive manufacturingtechniques and utilizes a basic structure comprised of a latticestructure. The lattice structure may ensure and/or contribute to afree-form structure having a defined rigidity and the lattice structuremay also ensure optimal coverage on the dentition by a coating materialwhich may be provided on the lattice structure. The lattice structure isat least partly covered by, impregnated in, and/or enclosed by thecoating material. Furthermore, embodiments of the lattice structure cancontribute to the transparency of the structure.

The term “free-form lattice structure”, as used herein, refers to astructure having an irregular and/or asymmetrical flowing shape orcontour, more particularly fitting at least part of the contour of oneor more body parts. Thus, in particular embodiments, the free-formstructure may be a free-form surface. A free-form surface refers to an(essentially) two-dimensional shape contained in a three-dimensionalgeometric space. Indeed, as detailed herein, such a surface can beconsidered as essentially two-dimensional in that it has limitedthickness, but may nevertheless to some degree have a varying thickness.As it comprises a lattice structure rigidly set to mimic a certain shapeit forms a three-dimensional structure.

Typically, the free-form structure or surface is characterized by a lackof corresponding radial dimensions, unlike regular surfaces such asplanes, cylinders and conic surfaces. Free-form surfaces are known tothe skilled person and widely used in engineering design disciplines.Typically non-uniform rational B-spline (NURBS) mathematics is used todescribe the surface forms; however, there are other methods such asGorden surfaces or Coons surfaces. The form of the free-form surfacesare characterized and defined not in terms of polynomial equations, butby their poles, degree, and number of patches (segments with splinecurves). Free-form surfaces can also be defined as triangulatedsurfaces, where triangles are used to approximate the 3D surfaces.Triangulated surfaces are used in Standard Triangulation Language (STL)files which are known to a person skilled in CAD design. The free-formstructures fit the surface of a body part, as a result of the presenceof a rigid basic structures therein, which provide the structures theirfree-form characteristics.

The term “rigid” when referring to the lattice structure and/orfree-form structures comprising them herein refers to a structureshowing a limited degree of flexibility, more particularly, the rigidityensures that the structure forms and retains a predefined shape in athree-dimensional space prior to, during and after use and that thisoverall shape is mechanically and/or physically resistant to pressureapplied thereto. In particular embodiments the structure is not foldableupon itself without substantially losing its mechanical integrity,either manually or mechanically. Despite the overall rigidity of theshape of the envisaged structures, the specific stiffness of thestructures may be determined by the structure and/or material of thelattice structure. Indeed, it is envisaged that the lattice structuresand/or free-form structures, while maintaining their overall shape in athree-dimensional space, may have some (local) flexibility for handling.As will be detailed herein, (local) variations can be ensued by thenature of the pattern of the lattice structure, the thickness of thelattice structure and the nature of the material. Moreover, as will bedetailed below, where the free-form structures envisaged herein compriseseparate parts (e.g. non-continuous lattice structures) which areinterconnected (e.g., by hinges or by areas of coating material), therigidity of the shape may be limited to each of the areas comprising alattice structure.

Generally, the methods envisaged herein are for dental appliancefabrication processes where the fabrication process includes designingan appliance worn on teeth to be covered by a free-form structure,manufacturing the mold, and providing the (one or more) latticestructures therein and providing the coating material in the mold so asto form the free-form structure. The free-form structures arepatient-specific, i.e. they are made to fit specifically on the anatomyor dentition of a certain patient, e.g., animal or human. FIG. 1Agenerally shows an overall exemplary method for fabricating a dentalappliance by capturing a 3D representation of a body part of a subject10. In this example, this may involve capturing the 3D representation ofthe surfaces, e.g. external contours, of a patient's dentition forcorrecting one or more malocclusions. For this purpose, the subject maybe scanned using a 3D scanner, e.g. a hand-held laser scanner, and thecollected data can then be used to construct a digital, threedimensional model of the body part of the subject. Alternatively, thepatient-specific images can be provided by a technician or medicalpractitioner by scanning the subject or part thereof. Such images canthen be used as or converted into a three-dimensional representation ofthe subject, or part thereof. Additional steps wherein the scanned imageis manipulated and for instance cleaned up may be envisaged.

With the captured 3D representation, a free-form structure comprisedgenerally of a lattice structure matching at least part of the surfaceof the body part, e.g., dentition, may be generated 12. Designing afree-form structure based on said three dimensional representation ofsaid body part, such that the structure is essentially complementary toat least part of said body part and comprises or consists of a latticestructure. In the lattice structure, one or more types and/or sizes ofunit cell may be selected, depending on the subject shape, the requiredstiffness of the free-form structure, etc. Different lattice structuresmay be designed within the free-form structure for fitting on differentlocations on the body part. The different lattice structures may beprovided with, e.g., a hinge or other movable mechanism, so that theycan be connected and/or, can be digitally blended together or connectedby beams in the basic structure to form a single part.

This step may also include steps required for designing the latticestructure, including for instances of defining surfaces on the positiveprint of the mask that may need different properties, different cellsizes and/or openings, generating the cells with the required geometryand patterning them as needed on the defined surfaces to cover saidsurfaces, and combining the separate cell patterns into a single solidpart. It should be noted that the requirements of the lattice structurewould be clear to a skilled person while designing the latticestructure. The skilled person will therefore use data obtained from hisown experience as well as data from numerical modeling systems, such asFE and/or CFD models.

The free-form lattice structure may then be actually manufactured, e.g.,by additive manufacturing methods 14. In certain embodiments, this mayinclude providing a coating material on the basic structure in whichcoating material is preferably a polymer. These different steps need notbe performed in the same location or by the same actors. Indeedtypically, the design of the free-form structure, the manufacturing andthe coating may be accomplished in different locations by differentactors. Moreover, it is envisaged that additional steps may be performedbetween the steps recited above. In coating or impregnating thefree-form basic structure, the lattice structure may be impregnated witha certain material, such as a polymer, thereby generating the free-formstructure. This may include steps such as adding the polymeric materialor other material into the dental appliance, curing the materialimpregnating the lattice structure and disassembling the dentalappliance.

After manufacturing the free-form structure, the structure may gothrough a number of post-process steps including for instance cleaningup and finishing the free-form structure. Moreover, other applicationsof forming a rigid free-form structure as described herein may alsoinclude applications for, but not limited to, therapeutic, cosmetic andprotective applications.

In one particular application, the use of the free-form structuresdescribed herein may be used in the care and treatment of damaged skinsurfaces, such as burn wounds. In further embodiments, the use of thefree-from structures described herein may be used in the care,protection, and treatment of undamaged skin surfaces. According toadditional particular embodiments, the use of a free-form structure asdescribed herein may be used for cosmetic purposes. In furtherembodiments, the use of a free-form structure as described herein may beused for the delivery of treatment agents to the skin. In otherparticular embodiments, the structure further comprises one or moretherapeutic compositions which may be embedded in the coating material.In yet further embodiments, the use of the structures described hereinmay be used as prosthetic devices, e.g., for replacing a body part,where the free-forms structure may be made to be identical to themissing body part.

FIG. 1B shows another overall exemplary process for fabricating a dentalappliance having a lattice structure similarly to that shown above inFIG. 1A. In this example, once the 3D representation has been captured10, the amount of force required to move a tooth or teeth may bedetermined and finite element analysis may be utilized to determine anappropriate thickness of aligner material needed for the associatedforce 10A to move a particular tooth or teeth. In this manner, one ormore oral appliances may be fabricated with varying material thicknessesin which regions which may not require much force are fabricated to havea relatively thinner region while regions of the appliance which mayrequire a greater amount of force to move the tooth or teeth may befabricated to have relatively thicker regions of material to create anoral appliance having directional strength (Differential Force)depending on the particular forces needed to correct particularmalocclusions. Simulations may be performed on the modeled dentition (oraligners) to confirm stress point handling for the various alignerthicknesses 10B.

Then as previously described, a free-form structure comprised generallyof a lattice structure matching at least part of the surface of the bodypart, e.g., dentition, may be generated 12 and the free-form latticestructure may then be actually manufactured, e.g., by additivemanufacturing methods 14. However, the one or more oral appliances maybe fabricated to have regions of relatively thickened and/or thinnedmaterial to accommodate the directional strength (Differential Force) ofthe oral appliances, as described in further detail below.

FIG. 2 shows a perspective view of an exemplary oral appliance 20 havingtwo parts 22 (for the upper dentition and lower dentition). As shown,the oral appliance 20 generally includes a lattice structure 24 whichcan be used in a process for manufacturing the final oral appliance. Inthe process, the lattice structure 24 may first be 3D printed in a shapewhich approximates the oral appliance to be fabricated for correctingthe malocclusion and the lattice structure may be positioned within adental appliance 26, 26′. Then, the dental appliance 26, 26′ containingthe formed lattice structure 24 may be filled with the impregnatingmaterial 28, e.g., polymer or other materials described herein. Aftersetting of the impregnating material 28, the dental appliance halves 26,26′ are removed to yield the coated oral appliance 20.

While the entire lattice structure 24 may be coated or impregnated bythe impregnating material 28, only portions of the lattice structure 24may be coated or particular surfaces of the lattice structure 24 may becoated while leaving other portions exposed. Variations of theseembodiments are described in further detail below with respect to theoral appliance 20 shown in FIG. 2.

As can be appreciated, an approach to 3D printed progressive aligners ofvarying and/or increasing thickness has certain advantages. For example,the rate of incremental increase in thickness may not be dependent onstandard thicknesses of sheet plastic available as an industrialcommodity. An optimal thickness could be established for the 3D printingprocess. For example, rather than being limited to the, e.g., 0.040,0.060 and 0.080 in, thickness sequence, a practitioner such as anorthodontist could choose a sequence such as, e.g., 0.040, 0.053 and0.066 in, thickness, for an adult patient whose teeth are known toreposition more slowly compared to a rapidly growing adolescent patient.

Given the concept that an aligner formed from thinner material generatesgenerally lower corrective forces than an identically configured alignerformed from thicker material, it follows that an aligner could be 3Dprinted so as to be thicker in areas where higher forces are needed andthinner in areas where lighter forces are needed. Having the latitude toproduce aligners with first a default thickness and then areas ofvariable thickness could be favorably exploited to help practitionersaddress many difficult day-to-day challenges. For example, anymalocclusion will consist of teeth that are further from their desiredfinished positions than other teeth. Further, some teeth are smallerthan others and the size of the tooth corresponds to the absolute forcethreshold needed to initiate tooth movement. Other teeth may seem to bemore stubborn due to many factors including the proximity of the tooth'sroot to the boundaries between cortical and alveolar bony support. Stillother teeth are simply harder to correctively rotate, angulate, orup-right than others. Still other teeth and groups of teeth may need tobe bodily moved as rapidly as possible over comparatively large spans toclose open spaces. For at least such reasons, the option of tailoringaligner thickness and thus force levels around regions containing largerteeth or teeth that are further from their desired destinations, orthose stubborn teeth allows those selected teeth to receive higherforces than small, nearly ideally positioned teeth.

The free-form lattice structure for the dental appliances can be atleast partially fabricated by additive manufacturing, (AM). Moreparticularly, at least the basic structure may be fabricated by additivemanufacturing using the lattice structure. Generally, AM can may includea group of techniques used to fabricate a tangible model of an objecttypically using 3D computer aided design (CAD) data of the object. Amultitude of AM techniques are available for use, e.g.,stereolithography, selective laser sintering, fused deposition modeling,foil-based techniques, etc. Selective laser sintering uses a high powerlaser or another focused heat source to sinter or weld small particlesof plastic, metal, or ceramic powders into a mass representing the 3Dobject to be formed. Fused deposition modeling and related techniquesmake use of a temporary transition from a solid material to a liquidstate, usually due to heating. The material is driven through anextrusion nozzle in a controlled way and deposited in the required placeas described among others in U.S. Pat. No. 5,141,680, which isincorporated herein by reference in its entirety and for any purpose.Foil-based techniques fix coats to one another by use of, e.g., gluingor photo polymerization or other techniques, and then cuts the objectfrom these coats or polymerize the object. Such a technique is describedin U.S. Pat. No. 5,192,539, which is incorporated herein by reference inits entirety and for any purpose.

Typically AM techniques start from a digital representation of the 3Dobject to be formed. Generally, the digital representation is slicedinto a series of cross-sectional layers which can be overlaid to formthe object as a whole. The AM apparatus uses this data for building theobject on a layer-by-layer basis. The cross-sectional data representingthe layer data of the 3D object may be generated using a computer systemand computer aided design and manufacturing (CAD/CAM) software.

The basic structure comprising the lattice structure may thus be made ofany material which is compatible with additive manufacturing and whichis able to provide a sufficient stiffness to the rigid shape of theregions comprising the lattice structure in the free-form structure orthe free-form structure as a whole. Suitable materials include, but arenot limited to, e.g., polyurethane, acrylonitrile butadiene styrene(ABS), polycarbonate (PC), PC-ABS, polyamide, polyamide with additivessuch as glass or metal particles, methylmethacrylate-acrylonitrile-butadiene-styrene copolymer, etc.

The lattice structure itself may be comprised of a rigid structure whichhas an open framework of, e.g., 3D printed lattices. Lattice structuresmay contain a plurality of lattices cells, e.g., dozens, thousands,hundreds of thousands, etc. lattice cells. Once the 3D model of thedentition is provided, the process may generate STL files to print thelattice version of the 3D model and create support structures wherenecessary. The system identifies where material is needed in anappliance and where it is not required, prior to placing and optimizingthe lattice.

The system may optimize dental lattices in two phases. First, it appliesa topology optimization allowing more porous materials with intermediatedensities to exist. Second, the porous zones are transformed intoexplicit lattice structures with varying material volume. In the secondphase, the dimensions of the lattice cells are optimized. The result isa structure with solid parts plus lattice zones with varying volumes ofmaterial. The system balances the relationship between material densityand part performance, for example, with respect to the stiffness tovolume ratio, that can impact design choices made early in the productdevelopment process. Porosity may be especially important as afunctional requirement for biomedical implants. Lattice zones could beimportant to the successful development of products where more than merestiffness is required. The system can consider buckling behavior,thermal performance, dynamic characteristics, and other aspects, all ofwhich can be optimized. The user may manipulate material density basedupon the result of an optimization process, comparing stronger versusweaker, or solid versus void versus lattice, designs. The designer firstdefines the objective, then performs optimization analysis to inform thedesign.

While 3D printing may be used, the lattices can also be made of strips,bars, girders, beams or the like, which are contacting, crossing oroverlapping in a regular pattern. The strips, bars, girders, beams orthe like may have a straight shape, but may also have a curved shape.The lattice is not necessarily made of longitudinal beams or the like,and may for example consist of interconnected spheres, pyramids, etc.among others.

The lattice structure is typically a framework which contains a regular,repeating pattern as shown in FIG. 2A, wherein the pattern can bedefined by a certain unit cell. A unit cell is the simplest repeat unitof the pattern. Thus, the lattice structure 24 is defined by a pluralityof unit cells. The unit cell shape may depend on the required stiffnessand can for example be triclinic, monoclinic, orthorhombic, tetragonal,rhombohedral, hexagonal or cubic. Typically, the unit cells of thelattice structures have a volume ranging from, e.g., 1 to 8000 mm³, orpreferably from 8 to 3375 mm³, or more preferably from 64 to 3375 mm³,or most preferably from 64 to 1728 mm³. The unit cell size maydetermine, along with other factors such as material choice and unitcell geometry, the rigidity (stiffness) and transparency of thefree-form structure. Larger unit cells generally decrease rigidity andincrease transparency, while smaller unit cells typically increaserigidity and decrease transparency. Local variations in the unit cellgeometry and/or unit cell size may occur, in order to provide regionswith a certain stiffness. Therefore, the lattice 24 may comprise one ormore repeated unit cells and one or more unique unit cells. In order toensure the stability of the lattice structure 24, the strips, bars,girders, beams or the like may have a thickness or diameter of, e.g.,0.1 mm or more. In particular embodiments, the strips, bars, girders,beams or the like may preferably have a thickness or diameter of, e.g.,0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 5 mm or more.The main function of the lattice structure 24 is to ensure a certainstiffness of the free-form structure. The lattice structure 24 mayfurther enhance or ensure transparency, as it is an open framework. Thelattice structure 24 can preferably be considered as a reticulatedstructure having the form and/or appearance of e.g., a net or grid,although other embodiments may be used.

The stiffness of the lattice structure depends on factors such as thestructure density, which depends on the unit cell geometry, the unitcell dimensions and the dimensions of the strips, bars, girders, beams,etc. of the framework 32. Another factor is the distance, S, between thestrips and the like, or in other words, the dimensions of the openingsin the lattice structure, as shown in the detail exemplary view of FIG.2B. Indeed, the lattice structure is an open framework and thereforecomprises openings 34. In particular embodiments, the opening size S ofthe lattice structure is between, e,g., 1 and 20 mm, between 2 and 15mm, or between 4 and 15 mm. In preferred embodiments, the opening sizeis between, e.g., 4 and 12 mm. The size of the openings may be the equalto or smaller than the size of the unit cell 34 while in otherembodiments, the openings may be uniform in size or arbitrary in size.In yet another alternative, differing regions of the lattice may haveopenings which are uniform in size but which are different from otherregions.

In particular embodiments, the free-form structures may comprise tolattice structure having one or more interconnected reticulated layers,as shown in the exemplary end view of FIG. 2C. For instance, the latticestructure may comprise one, two, three or more reticulated layers 38,where the structure comprises different at least partially superimposedand/or interconnected layers 36, 36′, 36″ within the lattice structure.The degree of stiffness provided by the lattice structure may increasewith the number of reticulated layers provided therein. In furtherparticular embodiments, the free-form structures may comprise more thanone lattice structure. The examples shown are merely illustrative of thedifferent embodiments.

For certain applications the lattice structure may further comprise oneor more holes with a larger size than the openings or unit cells asdescribed hereinabove. Additionally or alternatively, the latticestructure may not extend over the entire shape of the free-formstructure such that openings in the structure or regions for handling,tabs or ridges, and/or regions of unsupported coating material areformed. An example of such an application is a facial mask, where holesare provided at the location of the eyes, mouth and/or nose holes.Typically, these latter holes are also not filled by the coatingmaterial.

Similarly, in particular embodiments, the size of the openings which areimpregnated in and/or enclosed by the adjoining material may rangebetween, e.g., 1 and 20 mm. The holes in the lattice structure(corresponding to holes in the free-form structure) as described hereinwill also typically have a size which is larger than the unit cell.Accordingly, in particular embodiments, the unit cell size rangesbetween, e.g., 1 and 20 min.

According to particular embodiments, as shown in the end view of FIG.2D, the envisaged free-form structure may contain regions 33 comprisedonly of the coating material 31. This may be of interest in areas whereextreme flexibility of the free-form structure is desired.

In particular embodiments, the envisaged free-form structure maycomprise a basic structure which contains, in addition to a latticestructure, one or more limited regions which do not contain a latticestructure, but are uniform surfaces, as shown in the detail perspectiveview of FIG. 2E. Typically these form extensions 35 from the latticestructure with a symmetrical shape (e.g. rectangular, semi-circle,etc.). Such regions, however, typically encompass less than, e.g., 50%,or more particularly less than, e.g., 30%, or most particularly lessthan, e.g., 20% of the complete basic structure. Typically they are usedas areas for handling (manual tabs) of the structure and/or forplacement of attachment structures (clips, elastic string, etc.). Inparticular embodiments, the basic structure may be comprised essentiallyof only a lattice structure.

It can be advantageous for the dental appliance structure to havecertain regions with a different stiffness (such as in the molar teethto provide added force). This can be achieved by providing a latticestructure with locally varying unit cell geometries, varying unit celldimensions and/or varying densities and/or varying thicknesses of thelattice structure (by increasing the number of reticulated layers), asshown in the exemplary detail perspective view of FIG. 2F. Accordingly,in particular embodiments, the lattice structure is provided withvarying unit cell geometries, varying unit cell dimensions, varyinglattice structure thicknesses and/or varying densities 37, 39.Additionally or alternatively, as described herein, the thickness of thecoating material may also be varied, as shown in FIG. 2G. Thus, inparticular embodiments, the free-form structure has a varying thicknesswith a region of first thickness 41 and a region of second thickness 43.In further particular embodiments, the free-form structures may haveregions with a different stiffness, while they retain the same volumeand external dimensions.

In particular embodiments of the free-form structures, the basicstructure or the lattice structure can be covered in part with a coatingmaterial which is different from the material used for manufacturing thelattice structure. In particular embodiments the lattice structure is atleast partly embedded within or enclosed by (and optionally impregnatedwith) the coating material, as shown in the exemplary detail end view ofFIG. 2H. In further embodiments, the coating material is provided ontoone or both surfaces of the lattice structure 36. In particularembodiments only certain surface regions of the basic structure and/orthe lattice structure in the free-form structure are provided with acoating material while portions may be exposed 45. In particularembodiments, at least one surface of the basic structure and/or latticestructure may be coated 31 for at least 50%, more particularly at least80%. In further embodiments, all regions of the basic structure having alattice structure are fully coated, on at least one side, with thecoating material. In further particular embodiments, the basic structureis completely embedded with the coating material, with the exceptions ofthe tabs provided for handling.

In further embodiments, the free-form structure comprises, in additionto a coated lattice structure, regions of coating material not supportedby a basic structure and/or a lattice structure.

Accordingly, in particular embodiments, the free-form structure maycomprise at least two materials with different texture or composition.In other embodiments, the free-form structure may comprise a compositestructure, e.g., a structure which is made up of at least two distinctcompositions and/or materials.

The coating material(s) may be a polymeric material, a ceramic materialand/or a metal. In particular embodiments, the coating material(s) is apolymeric material. Suitable polymers include, but are not limited to,silicones, a natural or synthetic rubber or latex, polyvinylchloride,polyethylene, polypropylene, polyurethanes, polystyrene, polyamides,polyesters, polyepoxides, aramides, polyethyleneterephthalate,polymethylmethacrylate, ethylene vinyl acetate or blends thereof. Inparticular embodiments, the polymeric material comprises silicone,polyurethane, polyepoxide, polyamides, or blends thereof.

In particular embodiments the free-form structures comprise more thanone coating material or combinations of different coating materials.

In specific embodiments, the coating material is a silicone. Siliconesare typically inert, which facilitates cleaning of the free-formstructure.

In particular embodiments, the coating material is an opticallytransparent polymeric material. The term “optically transparent” as usedherein means that a layer of this material with a thickness of 5 mm canbe seen through based upon unaided, visual inspection. Preferably, sucha layer has the property of transmitting at least 70% of the incidentvisible light (electromagnetic radiation with a wavelength between 400and 760 nm) without diffusing it. The transmission of visible light, andtherefore the transparency, can be measured using a UV-VisSpectrophotometer as known to the person skilled in the art. Transparentmaterials are especially useful when the free-form structure is used forwound treatment (see further). The polymers may be derived from one typeof monomer, oligomer or prepolymer and optionally other additives, ormay be derived from a mixture of monomers, oligomers, prepolymers andoptionally other additives. The optional additives may comprise ablowing agent and/or one or more compounds capable of generating ablowing agent. Blowing agents are typically used for the production of afoam.

Accordingly, in particular embodiments, the coating material(s) arepresent in the free-form structure in the form of a foam, preferably afoamed solid. Thus, in particular embodiments, the lattice structure iscoated with a foamed solid. Foamed materials have certain advantagesover solid materials: foamed materials have a lower density, requireless material, and have better insulating properties than solidmaterials. Foamed solids are also excellent impact energy absorbingmaterials and are therefore especially useful for the manufacture offree-form structures which are protective elements (see further). Thefoamed solid may comprise a polymeric material, a ceramic material or ametal. Preferably, the foamed solid comprises one or more polymericmaterials.

The foams may be open cell structured foams (also known as reticulatedfoams) or closed cell foams. Open cell structured foams contain poresthat are connected to each other and form an interconnected networkwhich is relatively soft. Closed cell foams do not have interconnectedpores and are generally denser and stronger than open cell structuredfoams. In particular embodiments, the foam is an “integral skin foam”,also known as “self-skin foam”, e.g., a type of foam with a high-densityskin and a low-density core.

Thus in particular embodiments, free-form structures may comprise abasic structure which includes a lattice structure which is at leastpartially coated by a polymeric or other material as described herein.For some applications, the thickness of the coating layer and theuniformity of the layer thickness of the coating are not essential.However, for certain applications, it can be useful to provide a layerof coating material with an adjusted layer thickness in one or morelocations of the free-form structure, for example, to increase theflexibility of the fit of the free-form structure on the body part.

The basic structure of the freeform structures envisaged herein can bemade as a single rigid free-form part which does not need a separateliner or other elements. Independent thereof it is envisaged that thefree-form structures can be further provided with additional components47 such as sensors, straps, or other features for maintaining thestructure in position on the body, or any other feature that may be ofinterest in the context of the use of the structures and integratedwithin or along the structure, as shown in FIG. 2I. Various examples ofsensors which may be integrated are described in further detail herein.

In certain embodiments, the free-form structure comprises a single rigidlattice structure (optionally comprising different interconnected layersof reticulated material). However, such structures often only allow alimited flexibility, which may cause discomfort to a person or animalwearing the free-form structure. An increase in flexibility can beobtained if the free-form structure comprises two or more separate rigidlattice structures which can move relative to each other. These two ormore lattice structures are then enclosed by a material as describedabove, such that the resulting free-form structure still is made orprovided as a single part. The rigidity of the shape of the free-formstructure is ensured locally by each of the lattice structures, whileadditional flexibility during placement is ensured by the fact thatthere is a (limited) movement of the lattice structures relative to eachother. Indeed, in these embodiments, the coating material and/or a morelimited lattice structure) will typically ensure that the latticestructures remain attached to each other.

In particular embodiments, the lattice structures are partially orcompletely overlapping. However, in particular embodiments, thedifferent lattice structures are non-overlapping. In further particularembodiments, the lattice structures are movably connected to each other,for example via a hinge or other movable mechanism 49, 49′, as shown inthe detail end view of FIG. 2J. In particular embodiments the connectionis ensured by lattice material. In further particular embodiments thelattice structures may be interconnected by one or more beams which formextensions of the lattice structures. In further embodiments the latticestructures are held together in the free-form structure by the coatingmaterial. An example of such a free-form structure is a facial mask witha jaw structure that is movable with respect to the rest of the mask.Accordingly, in particular embodiments, the lattice structure comprisesat least two separate lattice structures movably connected to eachother, whereby the lattice structures are integrated into the free-formstructure, as shown.

The free-form structure may be used for wound treatment as describedherein. For optimal healing, the free-form structure provides a uniformcontact and/or pressure on the wound site or specific locations of thewound site. The lattice structure makes it simple to incorporatepressure sensors into the free-form structure according to the presentinvention. The sensors can be external sensors, but may also be internalsensors. Indeed, the lattice structure can be designed such that itallows mounting various sensors at precise locations, as describedabove, before impregnating and/or enclosing the lattice structure by apolymer or other material.

Additionally or alternatively, the free-form structure may comprise oneor more other sensors, as described above in FIG. 2I, such as atemperature sensor, a moisture sensor, an optical sensor, a straingauge, an accelerometer, a gyroscope, a GPS sensor, a step counter, etc.Accelerometers, gyroscopes, GPS sensors and/or step counter may forexample be used as an activity monitor. Temperature sensor(s), moisturesensor(s), strain gauge(s) and/or optical sensor(s) may be used tomonitor the healing process during wound treatment. Specifically, theoptical sensor(s) may be used to determine collagen fiber structure asexplained in US Pat. App. 2011/0015591, which is hereby incorporated byreference in its entirety and for any purpose.

Accordingly, in particular embodiments the free-form structure furthercomprises one or more external and/or internal sensors. In specificembodiments, the free-form structure comprises one or more internalsensors. In certain embodiments, the free-form structure comprises oneor more pressure and/or temperature sensors.

The skilled person will understand that in addition to the sensor(s),also associated power sources and/or means for transmitting signals fromthe sensor(s) to a receiving device may be incorporated into thefree-form structure, such as wiring, radio transmitters, infraredtransmitters, and the like.

In particular embodiments, at least one sensor may comprisemicro-electronic mechanical systems (MEMS) technology, e.g., technologywhich integrates mechanical systems and micro-electronics. Sensors basedon MEMS technology are also referred to as MEMS-sensors and such sensorsare small and light, and consume relatively little power. Non-limitingexamples of suitable MEMS-sensors are the STTS751 temperature sensor andthe LIS302DL accelerometer STMicroelectronics.

As shown in FIG. 2K, the lattice structure also allows providing thefree-form structure with one or more (internal) channels 51. Thesechannels may be used for the delivery of treatment agents to theunderlying skin, tissue, or teeth. The channels may also be used for thecirculation of fluids, such as heating or cooling fluids.

One philosophy of orthodontic treatment is known as “Differential Force”called out for the corrective forces directed to teeth to be closelytailored according to the ideal force level requirements of each tooth.The Differential Force approach was supported by hardware based oncalibrated springs intended to provide only those ideal force levelsrequired. Carrying the concepts of the Differential Force approachforward to the precepts of aligner fabrication, one can appreciate thatCNC-machined aligners exhibiting carefully controlled variable thicknesscan accomplish the Differential Force objectives on a tooth-by-toothbasis. The compartments surrounding teeth can have wall thicknessesestablished at the CAD/CAM level by a technician based on the needs ofeach tooth. A 3D printed aligner can have a limitless series of regions,each with a unique offset thickness between its inner and outersurfaces.

Prior to installing such devices, a practitioner may assess the progressof a case at mid-treatment for example and in particular, make note ofproblem areas where the desired tooth response is lagging or instanceswhere particular teeth are stubbornly not moving in response totreatment forces. The 3D printed structure can include a group of smalldevices that are intended to be strategically positioned and 3D printedwith an aligner's structure. Such devices are termed “alignerauxiliaries.” FIG. 3 is a detail view of a portion of an aligner 40showing a 3D printed area 42 that is machined allowing thicker materialto accept an elastic 44. Other 3D printed geometries of interest wouldbe divots or pressure points, creating openings/windows on the alignerfor a combination treatment, e.g., forming hooks on the aligner forelastic bands, among others. Aligner auxiliaries may be installed inthose locations to amplify and focus corrective forces of the aligner toenhance correction. For example, an auxiliary known as a tack can beinstalled after a hole of a predetermined diameter is pierced through awall of a tooth-containing compartment of an aligner. The diameter ofthe hole may be slightly less than the diameter of a shank portion ofthe tack which may be printed directly on the aligner. Suchprogressively-sized tacks and other auxiliary devices are commerciallyavailable to orthodontists who use them to augment and extend the toothposition correcting forces of aligners.

Bumps can also be used and serve to focus energy stored locally in theregion of the aligner's structure adjacent to a bump. Theinward-projecting bump causes an outward flexing of the aligner materialin a region away from the tooth surface. Configured in this way, bumpsgather stored energy from a wider area and impinge that energy onto thetooth at the most mechanically advantageous point, thus focusingcorrective forces most efficiently. An elastic hook feature 50 can be 3Dprinted directly in an otherwise featureless area of an aligner'sstructure, as shown in the side views of FIGS. 4A and 4B. Elastic hooksmay also be used as anchor points for orthodontic elastics that providetractive forces between sectioned portions of an aligner (or an alignerand other structures fixedly attached to the teeth) as needed duringtreatment.

Aside from hook features 50, other features such as suction features 52may he fabricated for adherence to one or more particular teeth T, asshown in the partial cross-sectional view of FIG. 4C. In this manner,the aligner may exert a directed force 54 concentrated on the one ormore particular teeth.

In yet another embodiment, as shown in the perspective view of FIG. 4D,the occlusal surfaces of the aligner may be fabricated to have areasdefined to facilitate eating or talking by the patient. Such featuresmay include occlusal regions which are thinned, made into flattenedsurfaces 56, or made with any number of projections 58 to facilitateeating.

Additionally, different portions of the aligners may be fabricated tohave different areas 60 of varying friction, as shown in the perspectiveview of FIG. 4E. Such varying areas may be formed, e.g., along the edgesto prevent tearing of the aligner material,

Additional attachments can be formed on the 3D printed dental appliancessuch as particulate coatings. The particulate coating 62 may be formedon the tooth engaging surface of the lattice 3D printed appliance in anyconvenient manner, e.g., fusion, sintering, etc., as shown in theperspective view of FIG. 4F. The particles making up the coating may beany convenient shape, including a spherical shape or an irregular shape,and may be constructed of metal (including alloys), ceramic, polymer, ora mixture of materials. The particulate coating adhered to the toothengaging surface may take the form of discrete particles which arespaced apart from each other on the surface, or the form of a layer ormultiple layers of particles bonded together to produce a network ofinterconnected pores. The particulate coating provides a porousinterface into which a fluid bonding resin may readily flow andpenetrate. Upon curing of the resin to solid form, mechanical interlockis achieved between the cured resin and the particulate coating. Undersome circumstances chemical bonding in addition to this mechanicalbonding may be achieved, e.g., by the use of polycarboxylate or glassionomer cements with stainless steel and other metallic substrates andwith ceramic substrates.

For a coating of integrally-joined particles which make up a porousstructure having a plurality of interconnected pores extendingtherethrough, the particles are usually about −100 mesh and preferably amixture of particles of varying particle sizes restricted to one ofthree size ranges, e.g., −100+325 mesh (about 50 to about 200 microns),−325+500 mesh (about 20 to about 50 microns), and −500 mesh (less thanabout 20 microns). The size of the particles in the porous structuredetermines the pore size of the pores between the particles.Smaller-sized pores are preferred for fluid resin bonding agents whereaslarger-sized pores are preferred for more viscous cementitious bondingmaterials. The selection of particle size is also used to control theporosity of the coating to within the range of about 10 to about 50% byvolume.

An adequate structural strength is required for the composite ofsubstrate and coating, so that any fracture of the joint of the bracketto the tooth occurs in the resin and not in the coating. To achieve thiscondition, the structural strength of the coating, the interface betweenthe coating and the substrate and the substrate itself is at least 8MPa.

FIGS. 5A to 5D show exploded views of alternative lattice structureswhich may be utilized in any of the embodiments described herein. Thelattice structures have open faces and are layered and can also beregarded as two or more interconnected reticulated layers or asstructures comprising only one layer or more than two layers.

FIG. 5A shows a first and second perspective view of the latticestructure 70 having a triangular cell pattern and an example of thestructure 70 reconfigured into an alternative or compressedconfiguration 70′. FIG. 5B shows a first and second perspective view ofthe lattice structure 72 having a polygonal cell pattern and an exampleof the structure 72 reconfigured into an alternative or compressedconfiguration 72′. FIG. 5C shows a first and second perspective view ofthe lattice structure 74 having a diamond cell pattern and an example ofthe structure 74 reconfigured into an alternative or compressedconfiguration 74′. FIG. 5D shows a perspective view of the latticestructure 76 having a linked diamond cell pattern.

The applications of the devices and methods discussed above are notlimited to the use on the dentition but may include any number offurther treatment applications. Moreover, such devices and methods maybe applied to other treatment sites within the body. Modification of theabove-described assemblies and methods for carrying out the invention,combinations between different variations as practicable, and variationsof aspects of the invention that are obvious to those of skill in theart are intended to be within the scope of the claims.

What is claimed is:
 1. A method for fabricating an oral appliance, comprising: capturing a three-dimensional representation of a dentition of a subject; generating a free-form structure having a lattice structure which matches at least part of a surface of the dentition, wherein the lattice structure defines a plurality of open spaces such that the free-form structure is at least partially transparent; and manufacturing the lattice structure by impregnating or covering a coating into or upon the lattice structure such that the oral appliance is formed.
 2. The method of claim 1 further comprising generating one or more additional free-form structures and further manufacturing the one or more additional free-form structures to form one or more additional oral appliances, wherein each of the one or more additional oral appliances are configured to correct for malocclusions within the dentition.
 3. The method of claim 1 wherein generating a free-form structure further comprises determining a force required to move a tooth and modifying a thickness of the free-form structure in proximity to the tooth.
 4. The method of claim 3 wherein determining a force comprises performing a simulation to confirm a stress point for the free-form structure in proximity to the tooth.
 5. The method of claim 1 wherein generating a free-form structure comprises having the lattice structure define a plurality of open spaces which are uniform to one another.
 6. The method of claim 1 wherein generating a free-form structure comprises having the lattice structure define a plurality of open spaces which vary relative to one another.
 7. The method of claim 1 wherein generating a free-form structure comprises having two or more lattice structures in proximity to one another.
 8. The method of claim 1 wherein generating a free-form structure comprises varying a thickness of the lattice structure.
 9. The method of claim 1 wherein manufacturing the lattice structure comprises varying a thickness of the coating.
 10. The method of claim 1 wherein manufacturing the lattice structure further comprises defining one or more features upon the oral appliance.
 11. The method of claim 10 wherein the one or more features comprises regions of varied friction over a surface of the oral appliance.
 12. The method of claim 10 wherein the one or more features comprises projections extending from a surface of the oral appliance.
 13. The method of claim 1 wherein manufacturing the lattice structure comprises impregnating or covering a portion of the lattice structure.
 14. The method of claim 1 wherein manufacturing the lattice structure comprises impregnating or covering the lattice structure with a particulate coating.
 15. The method of claim 1 further comprising forming one or more channels through the coating.
 16. The method of claim 1 further comprising integrating one or more sensors within or upon the oral appliance.
 17. The method of claim 16 further comprising sensing forces on the lattice structure via the one or more sensors.
 18. An oral appliance for correcting one or more malocclusions in a subject, comprising: a lattice structure configured to match at least part of a surface of a dentition of the subject, wherein the lattice structure defines a plurality of open spaces such that the free-form structure is at least partially transparent; a coating impregnating; or covering into or upon the lattice structure; and a dental attachment structure formed as part of the lattice structure, wherein the dental attachment structure is located in proximity to one or more teeth to be moved.
 19. The oral appliance of claim 18 wherein the lattice structure is defined by a plurality of unit cells with a size between 1 and 20 mm.
 20. The oral appliance of claim 18 wherein the lattice structure comprises at least two lattice structures movably connected to one other and integrated into oral appliance.
 21. The oral appliance of claim 18 wherein the lattice structure has varying unit cell geometries.
 22. The oral appliance of claim 18 wherein the lattice structure has varying unit cell dimensions.
 23. The oral appliance of claim 18 wherein the lattice structure has varying lattice structure densities.
 24. The oral appliance of claim 18 wherein the coating comprises a plastic, polymer, ceramic, or metal material.
 25. The oral appliance of claim 24 wherein the polymer comprises silicone, polyurethane, polyepoxide, polyamides, or blends thereof.
 26. The oral appliance of claim 18 wherein the coating has a varying thickness.
 27. The oral appliance of claim 18 further comprising one or more sensors within or upon the oral appliance. 